Engineering Problem: Multi-game Launcher

Hi guys, I'm a C/C++ game developer of 10 years turned iPhone game developer for 2 years. I am now trying to begin work on an API/game engine which will feature a multi-game launcher that would let any developer (or a good number of developers) to "plug in" their game into my multi-game launcher with minimal effort.

My rough idea is creating an API that would take in a selector for a render loop and an update loop and have a singleton entity that will handle switching between games, saving game state, high scores, and all those other features common in all, if not, most games.

I would like to ask for thoughts/guidance/advice from you iPhone game dev gurus out there in how to implement this. Thanks in advance!